Dentin is the primary component of tooth structure and it microstructure and properties are the principal determinants of nearly all operations in restorative dentistry. Critical information on the structure, chemistry and properties of this complex composite material is not known. This program project grant proposes to conduct a series of independent but inter-related research programs to provide this information. The objective of the Administrative and Laboratory Core is the coordination of a variety of investigators' research and consultant expertise in areas of dentin structure, adhesion and bonding, and analytical techniques. In addition the core will maintain and control specimens, patient and specimen records, coordinate results, review progress, and provide for timely dissemination of new information generated from the five projects of the programs. The investigators and equipment are from three sites of the University of California, namely the San Francisco Campus (UCSF), Lawrence Livermore National Laboratory (LLNL), and Lawrence Berkeley Laboratory (LBL). The consultants represent prominent laboratories and related industries. The aims are: 1. to create Internal (IRB) and External Review Boards (ERB) for oversight of all aspects of the Program; 2. to integrate and review all research projects; 3. provide a central location for information collection and analysis; 4. to create an environment for collaboration between a diverse group with expertise in various aspects of materials and biological structural characterizations. This will permit the generation of new information on effects of post extraction history (Project I), basic structural and chemical information at the microstructural to ultrastructural level (Project II), the development of three dimensional x-ray tomographic microscopy or non-invasive high resolution dentin imaging (Project III), the nature and adhesive mechanisms available in dentin collagen (Project IV), and laser induced modifications of dentin structure for bonding of restorative materials (Project V). The responsibilities of the Core include the centralized collection of project information, specimen and record maintenance and distribution, analysis of data, correlation of data between projects, organization of IRB/ERB meetings, and the publication of new information resulting from the studies. The results of dentin characterization, adhesion, and modification will have a major impact on our understanding of dentin as a complex anisotropic composite material which can be modified to provide new adhesive techniques for restorative dentistry.